1. Field of the Invention
The invention relates to intergrating angular accelerometers for measuring angular rate of a rotating body. An accelerometer constructed according to the invention can be used for sensing angular velocities that are varying relatively rapidly.
2. Brief Description of the Prior Art
Angular accelerometers as used heretofore, such as shown and described in U.S. Pat. No. 3,819,234, provide acceleration signals and, in order to obtain angular rate, the signals must be intergrated, usually by electronic means. Noise is a serious problem which must be overcome to provide useful angular rate signals; U.S. Pat. No. 4,002,077, which is incorporated by reference, presents a solution to this problem by using a large hydrostatic bearing to support the inertial mass. In the device of the latter patent, an annular channel of laminar dimensions is provided between the internal mass and the base groove. The housing, including the channel, is filled with viscous fluid and the inertial mass is supported in the fluid. When the housing rotates relative to the inertial mass, upon angular acceleration of the device in which the accelerometer is housed, a pressure differential proportional to the angular rate is provided across two pick-off ports connected to the annular channel. This is due to the viscous pumping effect caused by relative motion between the housing and inertial mass. Signals of a relatively large band width that are substantially noise free are provided. The device is relatively simple in construction in that it comprises only two parts, an inertial mass or wheel supported by a hydrostatic bearing and a housing filled with viscous fluid.
Standard floated spinning wheel rate sensors have been used but with what is usually a highly shortened life due to the extreme shock and vibration amplitudes found on tanks and other heavy armament systems. Fluidic sensors are another alternative but they generally have low output signals thus requiring signal amplification using fluidic amplifiers, etc.